There aren’t many, but I’m a huge fan of Mammoth, if you want to go a little bit further:

http://www.mammothmountain.com

We loved Sierra Ski Ranch. I haven’t been there in a while but it was “least” crowded. And we wondered why because its really beautiful there. Its a little hidden treasure.

Kirkwood is good if you have transportation. Or Sierra- at-Tahoe is also good. There are more choices at Nothe Lake Tahoe. You should also consider the average abilities of your group.